Contact with aliens happened, but not the way people imagined it. The aliens turned Earth—more precisely, Moscow—into a zone. Yes, the very real penal labor colony where they dump all sorts of alien creatures that, in factories, sew alien mittens.
Moscow is surrounded by an impenetrable force field—you can get in, but you can’t break out and escape. Earthlings, sensing this, send into that zone all their own scum: criminals, pushers of narcotics, terrorists, political offenders…
And in this mess manages to survive the GG known by the nickname Farmer. He’s called Farmer because he grows tomatoes, but the book is not really about that. It’s about how Uncle Fedor learns that Moscow is a pilot project of those nasty, claw-handed aliens—and that soon all of Earth will be covered with similar zones and turned into a planet-penal colony.